Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UK

G. DavidBatty

Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UKCentre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK

Martin J.Shipley

Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UK

AnnieBritton

Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UK

Eric J.Brunner

Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UK

JussiVahtera

Finnish Institute of Occupational Health, Lemminkäisenkatu 14–18b, 20520Turku, FinlandDepartment of Public Health, University of Turku, and Turku University Hospital, Turku, Finland